“…• in [48], Ω is just a bounded domain in R 2 , the elasticity coefficients satisfy a ijkh ∈ W 1,∞ (Ω), and are further required to meet a special spectral condition (see (2.17) in [48]) • in [2], Ω is a bounded domain in R N , (N ≥ 2), and the material is isotropic: a ijkh (x) = 2µ(x)δ ik δ jh + λ(x)δ ij δ kh , where λ, µ ∈ C 1,1 (Ω) with µ(x) ≥ α 0 and 2µ(x) + λ(x) ≥ β 0 , for all x ∈ Ω, for some positive constants α 0 and β 0 . • in [70], Ω is a bounded domain in R 3 , (N = 3), and the material is isotropic as in the second point above, with λ and µ being Lipschitz continuous, and further satisfying the coerciveness conditions above.…”